Question

The work done by an uniform magnetic field, on a moving charge is

• A. zero because $\vec{F}$ acts parallel to $\vec{v}$
• B. positive because $\vec{F}$ acts perpendicular to $\vec{v}$
• C. zero because $\vec{F}$ acts perpendicular to $\vec{v}$
• D. negative because $\vec{F}$ acts parallel to $\vec{v}$

Answer 1

Answer: (C)

Force on moving charge while moving in magnetic field is; $\vec{F}=q\left(\vec{v}\times\vec{B} \right)$ where $\vec{F}$ is perpendicular to $\vec{v}$
Work done/sec $=\vec{F},\vec{v}=Fv\,cos\,90º=0$